1. Field of the Invention
The present invention relates to a semiconductor wafer which is useful for electronic devices and formation of integrated circuits, and a process for the production thereof. More particularly, the present invention relates to a semiconductor wafer comprising a monocrystalline semiconductor layer, and a process for production thereof.
2. Related Background Art
Formation of a thin monocrystalline semiconductor layer on an insulating layer is well known as silicon-on-insulator (SOI) technique. The devices obtained from the wafer of the SOI structure are comprehensively investigated since the devices has many advantages which are not achievable by use of a bulk monocrystalline Si wafer for usual Si integrated circuits. Recent researches on the process for production of the above wafers are roughly classified into three types of processes as below:
(1) processes comprising steps of oxidizing the surface of a monocrystalline Si substrate, forming partially an aperture in the SiO.sub.2 layer to expose partially the monocrystalline Si substrate, and growing epitaxially monocrystalline Si in the lateral direction by utilizing the monocrystalline Si as the seed at the aperture portion to form a monocrystalline Si layer on the SiO.sub.2. PA0 (2) processes utilizing the monocrystalline Si substrate itself as the active layer, which comprises a step of forming an SiO.sub.2 layer under a surface monocrystalline Si layer of a monocrystalline Si substrate with retaining the surface monocrystalline Si layer. PA0 (3) processes comprising steps of growing Si monocrystal epitaxially on a monocrystalline Si substrate, and carrying out an insulative separation.
Neither of the SOI techniques give more than a single layer of a monocrystalline semiconductor layer on an insulating layer, and giving a device which utilizes a monocrystalline semiconductor layer two-dimensionally on the insulating layer.